Rocks Flashcards
Is an aggregate of one or more minerals w/c may or may not contain glass, organic matter and mineraloids.
rocks
3 types of rocks
–Igneous rocks
–Sedimentary rocks
–Metamorphic rocks
Study of Rocks
petrology
Igneous Rocks are formed by ______, _______, and ________ of other rocks.
melting
cooling
crystalization
are formed when magma hardens beneath Earth’s surface.
intrusive igneous rocks
are formed when lava hardens.
extrusive igneous rocks
Intrusive igneous rocks are formed when magma hardens beneath Earth’s surface.
plutonic rocks
Extrusive igneous rocks are formed when lava hardens.
volcanic rocks
The larger the crystals,
the slower it cooled
The smaller the crystals
the faster it undergone cooling process.
Igneous rocks are classified using their texture in the following ways:
–Glassy
–Aphanitic
–Phaneritic
–Porphyritic
igneous rocks have no crystal structure, and probably formed by very rapid cooling (such as on the surface of a lava, or when a lava enters the water.)
Glassy
rocks have no visible crystals, and probably formed by fast cooling above ground. This are extrusive igneous rock
Ex. Basalt and rhyolite
Aphanitic or fine grained
rocks have visible crystals, and probably formed by slow cooling below ground. Intrusive igneous rocks.
Ex. Granite
Phaneritic or coarse grained
rocks have both visible and nonvisible crystals, and probably formed by two different cooling events.
phorphyritic
2 types of Dark igneous rocks
-Ultramafic
-Mafic
_________igneous rocks contains ferromagnesian (45% silica content)
Ultramafic
_________igneous rock contains a lot of magnesium and iron. (45-55% silica content)
Mafic
2 types of light colored igneous rocks
Intermediate
felsic
The most common types of igneous rocks include:
–Rhyolite
–Andesite
–Basalt
–Granite
–Diorite
–Gabbro
Sedimentary rocks are formed by ______, ________, ________, _______, and ________ of other rocks.
weathering
erosion
deposition
compaction
cementation
Sedimentary rocks form in areas where ____, ____, or _____ deposit sediments.
water
wind
gravity
Sedimentary rocks are likely to form in areas such as:
–Deltas
–Beaches
–Rivers
–Glaciers
–Sand dunes
–Shallow seas
–Deep oceans
Processes that rock convert into loose sediments
weathering
erosion
when wind and water break rock down into smaller pieces, or sediment.
weathering
the movement of sediments by wind, water, gravity, or other natural forces.
erosion
loose fragments of rock, minerals and organic material that result from the breakdown of rock by weathering.
sediments
the depositing and accumulation of sediment in an area.
deposition
the process in which sediment is squeezed and the space in between grains is reduced by the weight of the overlying layers.
compaction
the process in which sediments are glued together by minerals as water evaporates.
cementation
Types of sedimentary rocks are determined by processes in which the rocks form and their composition.
•Chemical Sedimentary Rock (CSR)
•Organic Sedimentary Rock (OSR)
•Clastic Sedimentary Rock (CSR)
forms from minerals that were dissolved in water and as water evaporates minerals are left behind.
Chemical Sedimentary Rock (CSR)
forms from the remains of living things.
Organic Sedimentary Rock (OSR)
formed by rock fragments that are carried away from their source by water, wind, and ice and are compressed and glued together by minerals.
Clastic Sedimentary Rock (CSR)
Some of the most common types of sedimentary rocks include:
– Conglomerate
–Sandstone
–Shale
–Limestone
–Gypsum
–Oolites
rocks formed when existing rock is changed by heat and/or pressure.
Metamorphic Rock
the process in which heat, pressure, mechanical stresses and chemical processes change existing rock.
metamorphism
It all begins with an existing rock, like a sedimentary rock (made from layers of sand, mud, or other materials) or an igneous rock (formed from molten lava or magma).
start with a rock
Metamorphic rocks form when that original rock gets buried deep within the Earth’s crust, where it’s really hot and under a lot of pressure. This can happen due to tectonic forces pushing rocks deep underground.
heat and pressure
The high temperature and pressure cause the minerals and crystals in the original rock to change. They don’t melt, but they rearrange themselves into new patterns. It’s like the rock is getting a new look.
Transformation
After this transformation, the rock slowly makes its way back to the surface, either through geological forces or erosion. As it cools down, the new arrangement of minerals hardens into a metamorphic rock
cooling and hardening
Types of Metamorphism
•Contact Metamorphism
•Regional Metamorphism
a change in the texture, structure, or chemical composition of a rock due to contact with magma.
contact metamorphism
a change in the texture, structure, or chemical composition or a rock due to changes in temperature and pressure over a large area.
regional metamorphism
Metamorphic rocks are classified into 2 major groups:
foliated
non foliated
rocks form when differential pressure causes minerals to form in layers.
•These rocks will have stripes or planes that they will break easily along.
•These “stripes” don’t usually line up with the original bedding planes in sedimentary rocks.
foliated
metamorphic rocks formed in areas where the pressure from all sides was equal, so there is no “linear” quality to the rocks.
non foliated
Some common types of metamorphic rock include:
–Slate
–Schist
–Gneiss
–Amphibolite
–Marble
–Quartzite
